The control of auxiliary devices in motor vehicles by means of voice commands is known from the state of the art. The control elements of these devices comprise a microphone, disposed in the interior of the motor vehicle, and a voice command detection circuit. If, in addition to these devices, there are also car radios, radio transmitter and receiver devices for taxicabs or blowers located in the vehicle, which become acoustically operative in the interior, there is a danger that the voice commands issued by the driver are not recognized by the detection circuit or that the contents of conversations or radio broadcasts are mistaken for voice commands. There is the further danger that the transmission of a voice command which consists of a plurality of partial commands, such as the digits of a number, is broken off during a critical traffic situation and that the entire command must be repeated after the traffic situation is back to normal.
It has been suggested in a prior application to turn off or mute for a pre-determined period of time the devices which become acoustically operational in the vehicle interior, while the voice command is issued. This results in problems, if the command is intended to trigger the change in the setting of an acoustically operative device, for example setting the volume, because the volume continues to change until the voice command is recognized, even with the devices muted.